For many applications and in many contexts, it can be desirable to know the absolute speed of a person or vehicle. For instance, a pedestrian or a driver may simply want to know how fast they are moving (i.e., a speedometer). For 2D and/or 3D positioning purposes, it can be advantageous to fuse an absolute speed measurement with information from other position- or motion-dependent sensors. For instance, absolute speed measurements can be used to bound position drift in an inertial navigation system (INS).
Orthogonal frequency-division multiplexing (OFDM) modulation schemes are currently utilized in a large number of broadcast and 2-way radio frequency (RF) communication systems. Therefore, it can be beneficial to exploit OFDM for the purpose of speed estimation. However, current techniques of doing so can be difficult to implement due to the computational and memory requirements.